Looper spreader mechanisms for sewing machines



Sept. 27, 1955 F. F. ZElER LOOPER SPREADER MECHANISMS FOR SEWINGMACHINES Filed Oct. 17, 1951 2 Sheets-Sheet l SQ IN V EN TOR;

ATTORNEY F. F. ZEIER Sept. 27, 1955 LOOPER SPREADER MECHANISMS FORSEWING MACHINES 2 Sheets-Sheet 2 Filed Oct.

1 ix INVENTOR.

fiedericfi cf eier A T TORNE Y M s Eon SEWING The present inventionrelates to chain-stitch sewing machines andhasfora primary object toprovide an improved thread-lobp forming mechanism, particularly for thelooper-thread, of such machines. 1 t

More specifically, the present invention has for its ob ject to providea-positive thread-detaining means for seizing and holding the thread,andparticularly the looper thread, of a chain-stitch sewing machine toinsure proper formation of a thread triangle and enchaining of thelooper-thread with the needle thread; i"

Having in mind these and other objects that will'be evident from anunderstanding of this disclosure, apresently preferred embodiment ofthis invention is' hereinafter set forth in such detail as to enablethose skilled in the art to readily understand the function, operation,construction and advantages of it, when read in conjunction with theaccompanying drawings, in which:

Fig. 1 is a front end elevation of a two-needle, twothread,chain-stitch, feed-off-the-arm sewing machine, with the work-arm shownin vertical longitudinal section and including a thread detainingmechanism constructed in accordance with the present invention:

Fig. 2 is a horizontal section on an enlarged scale taken substantiallyon the line 2 2"of Fig. l, but'having the feed mechanism of the machineomitted to more clearly illustrate the inventionw r r Figs. 3 and 4 arefragmentary views on an enlarged scale of Fig, 2, showing the left-handportion of the workarm as seen in Fig. 2 and showing the mechanisms indifferent positions. I

Fig. 5 is a vertical section taken substantially on the line 5-5 ofFig.3. p

Figs. 6 and 7 are detail views in perspective of two of the componentelements of the thread-detaining mechamsm.

The machine that has been selected for purposes of illustrating thepreferred embodiment of the present invention is a two needle,two-third, chain-stitch, feed-olfthe-arm sewing machine substantially asdisclosed in. my co-pending U. S. patent'application, Serial No. 15,805,filed March 19, 1948, now Patent No. 2,623,484, dated December 30, 1952,to which reference may be made for a more complete understanding ofthedetails of the illustrated machine. The following description relatesmore particularly to those elements'ofthe machine that are necessary tocompletely understand the present invention.

The sewing machine illustrated in the drawings includes a frame 10having a vertically depending arm 11 carrying a horizontalwork-supporting cylinder-bed or arm 12 which is of very small diameterto permit small diameter articles to be sewed thereon. The work-arm 12is so disposed that the free end thereof underlies a head 13 in whichare journaled a needle-bar 141 and ajpresser-bar 15 carrying,respectively, a pair of needles 16 and a resser-foot 17. t

Mounted within the work-arm 12 is a feed-dog 18 that vance the work pastthe stitching mechanism. The feeddog 18 is carried upon one end of a.feed-bar 19 extending longitudinally of the Work-arm. The feed-bar 19 islongitudinally slidable and crosswise pivotally mounted on bearingblocks 20 embracing an eccentric pin 21 which provides for verticaladjustment of the blocks. Feed-advance and -return movements areimparted to the feed-bar 19 by a rock-lever 22 and feed-lift movementsby a link 23. The rock-lever 22 and link 23 are secured to the feed-bar19 in appropriate driving relation, and they receive their motions froma driven shaft 24 journaled horizontally in the frame 10 and having anend thereof projecting into the upper portion of the depending arm 11.The rock-lever 22 is driven by the shaft24 through an adjustableeccentric (not shown) to provide for adjusting the feed-stroke, and thelink 23 is driven by the shaft 24 through an eccentric and theappropriate driving connections.

The stitching mechanism in the present machine includes two threadedloopers 25, each adapted to co-act with the corresponding one of theneedles 16 in the formation of conventional two-thread chain-stitches.The loopers 25 are secured to one end of a carrier 26 that is pivoted atthe opposite end to a looper-bar 27 in order that the loopers can beswung outwardly into a readily accessible position for threading. Inaddition to the usual loop-seizing and loop-shedding movements, thepresent loopers are also moved sidewise in loop-spreading movements asthe thread is heldby loop-detaining mechanism hereinafter described.Therefore, the looper-bar 27 must be so mounted as to be longitudinallyslidable and transversely pivotable about a point intermediate its ends,which is accomplished in the present device by fulcrumblocks 28.Suitable guides such as the plates 29 and 30 and block 31 are providedto guide and steady the looperbar in its movements. The guide-plate 30which is adapted to overlie the looper-carrier 26 is secured to theunder side of a needle-guide 32 mounted on the wall of the work-arm 12as by screws 33, while the guideplate 29 and guide-block 31 are secureddirectly to the work-arm. I

Loop-seizing and loop-shedding movements, i. e., longitudinalreciprocation, is imparted to the looper-bar 27 by an oscillating arm 34secured to a vertical shaft 35 journaled in the depending arm 11 andhaving the free end thereof slidingly projecting through an upstandingpin 36 journaled for free turning movement in the looper-bar 27. Theshaft 35 is oscillated by a crank connection (not shown) with the shaft24. I

Loop-spreading movements, i. e. transverse oscillation about thefulcrum-blocks 28, are imparted to the looperbar 27 by a link 37 pivotedat opposite ends to the looperbar and to a rock-arm 38 secured to thelower end of a vertical-shaft 39 journaled in the arm 11 and oscillatedabout its longitudinal axis by an eccentric connection (not shown withthe shaft 24.

The loop-detaining mechanism comprises, an angle bracket 41 secured tothe side wall of the work-arm 12 as by screws 40, and to which ispivotally secured as by a screw 42, a movable or locking element 43,shown per se in Fig. 7, and an arm 44. IThe bracket 41 also has securedthereto as by screws 45, a stationary element 46 shown per se in Fig. 6.The arm 44 and locking-element 43 are adjustably secured together, as bya screw 47, and the arm 44 includes an extended portion carrying aroller 48 adapted to cooperate with a slotted camblock 49 secured to thelooper-bar 27.

With reference to Fig. 6, it-will be seen that the stationary element 46comprises'a flaLS'ubStan'tiaIly-rectangular base bar 50 havi'ng.a'downwardly pcje'cting transverse rib s1 that i's seated in' aided/e52? ai lmaminnqmr or: it) \f tlll! and on w th; hm; ,0

Patented Sept. 27, 1955 the bracket 41 which serves to properly positionthe element 46 longitudinally of the work-arm 12. As seen in Fig. 3, thebracket 41 is adjustable by virtue of the enlarged apertures throughwhich the screws extend. Apertures 53 are formed in the bar 50, whichapertures are adapted to receive the screws and are transverselyelongated to provide for adjustment. Secured to the one corner of thebar is an upstanding and forwardly extending arm 54 that carries at itsupper end a flat head member 55 which is slotted, as at 56.

Referring to Fig. 7, the locking element 43 comprises a flatsubstantially pear-shaped base member 57 provided with a large aperture58 adapted to receive the screw 42, and a smaller arcuate aperture 59 toadjustably receive the screw 47. Bent upwardly and forwardly from thebase member 57 is an arm 60 from the end of which is bent a head member61 provided with curved locking fingers 62. As seen in Figs. 1 and 5,the elements 43 and 46 are so dimensioned that, when they are mountedupon the bracket 41, the head 61 of the element 43 normally underliesthe head 55 of the element 46 with the slots 56 and spaces between thefingers 62 in registry, and as seen in Figs. 3 and 4, when the elementsare moved relatively, the locking fingers 62 of the head 61 are adaptedto extend across the respective slots 56 in the head 46 at the mouththereof to close the slots and thus convert them into enclosedapertures.

It will be obvious to those skilled in the art that the number of pairsof stitching instrumentalities employed would not alter the method ofoperation of the present machine. Thus, to simplify the followingdescription, even though a two needle machine has been disclosed theoperation thereof will be set forth as though it were provided only witha single needle and its cooperating looper. Also, for convenience, onthe drawings the needlethread is designated Tn and the looper-thread T1.

In operation, the looper-bar 27 is actuated through a four-motion cyclein timed relation to the actuation of the needle. To effect thefour-motion cycle, the looperbar is pivoted about the axis of thefulcrum blocks 28 and given lengthwise translation to impartsubstantially elliptical motion to the looper-carrying end thereof, themajor axis of the elliptical path being longitudinally of the work-arm12. During the loop-seizing movement of the stitching cycle, the loopermoves in a substantially straight line up the arm toward the needle, orto the right as seen in Figs. 3 and 4, at the same time that the needleis being withdrawn from the work and casting a thread loop in theneedle-thread Tn. The line of travel of the looper is designed to passon the left side of the needle looking up the arm 12 as seen in Figs. 3and 4, but sufficiently close thereto to enter the thread loop cast bythe needle. As the needle is completely withdrawn from the work, thelooper, which now extends through a loop in the needle-thread, continuesto travel up the arm where the point thereof passes just beneath thehead 61 of the element 43 of the spreader mechanism. One limb of theloop in the looper-thread Tl that has been carried through the loop inthe needle-thread Tn by the looper is then carried into a slot 56 in thestationary element 46. This point in the stitching cycle is illustratedin Fig. 3.

The next motion in the four-motion cycle of the looperbar 27 which, ofcourse, begins slightly before the termination of the previous motion,is a counterclockwise pivoting of the bar about the axis of the fulcrumblocks 28, which movement carries the cam-block 49 to the right lookingup the arm 12 in Fig. 4. Sidewise movement of the cam-block causes thearm 44 and the attached locking link 43 to pivot about the screw 42,moving the head 61 of the locking element to the left looking up the arm12 in Fig. 4. As the head 61 is moved relative to the stationary elementhead 55 in the direction indicated, the finger 62 moves into a positionacross the mouth of the slot 56, and since the one limb of thelooper-thread is lodged in the slot at this time, it thus becomes lockedtherein.

The following motion in the cycle, which is the loopshedding motion,comprises a lengthwise sliding movement of the looper-bar 27 while inthe sidewise pivoted condition. The loop in the looper-thread is held inthe detaining mechanism and the legs thereof extend in divergentdirections therefrom, one to the last stitch set in the work and theother to the looper. Thus, as the looper moves down the arm, the twolegs of the looperthread are pulled out at an acute angle to each other.

Although the angle is small it is nevertheless made sufficiently wide sothat the needle will with reasonable certainty pass between the two legsof the looper thread on its next penetration of the work. At the sametime that the two legs of the looper-thread are being pulled out, theneedle-thread loop through which the looper has previously passed,begins to slide off the looper, which movement is aided by the action ofthe thread take-up. The needle-thread loop that encloses thelooper-thread loop acts to form a triangle with the two legs of thelooper thread, through which the needle passes on its next penetration.To insure the proper formation of the thread triangle, theneedle-threadtake-up action is timed so that it will not be so great as to cause thelegs of the looper thread to be drawn together and thus destroy thespacing between them, until after the needle has entered therebetween.

Near the completion of the lengthwise motion of the loper-bar 27 downthe work-arm 12, which position is illustrated in Fig. 4, the loop inthe needle-thread is pulled off the looper. At this time, the needle hasagain penetrated the work and entered the thread triangle. Completion ofthe take-up action on the needle-thread sets the stitch in the work,which stitch comprises a loop of the needle-thread through which hasbeen passed a loop of the looper-thread.

To complete the cycle, the looper-bar is pivoted clockwise about theaxis of the fulcrum blocks 28 into position to begin again the cycle asabove set forth, which pivotal movement acts to move the head 61 of thelocking element 43 relative to the head 55, and thus opens the slots 56therein and permits the looper-thread to be withdrawn therefrom and setin the work.

It will be obvious to those skilled in the art that variousmodifications may be made in the details of the looperthread-detainerwithout departing from the broader aspects to the present invention. Forthe lack of a better term, the looper-thread-detainer is referred to inthe following claims as including a locking means which is intended toinclude all Structural equivalents of the mechanism disclosed. Inparticular, the provision of a looper-thread-detainer that positivelylocks or clamps the looper-thread is intended to be included within thescope of the term locking means as used in the following claims.

Having thus set forth the nature of the invention, what I claim hereinis:

1. In a sewing machine having a work-support, a looper-barcarriedlongitudinally of the work-support, a looper secured to the looper-bar,and actuating mechanism adapted to impart four-motion cycles of movementto the looper-bar to produce movements of said looper about asubstantially elliptical path the major axis of which is longitudinallyof the work-support and the long sides of which constitute loop-seizingand loop-shedding movements, a stationary element carried by theworksupport including a head located adjacent the forward edge of thelooper when at the end of its loop-seizing motion, a movable elementpivotally carried by the worksupport and including a head locatedadjacent the head of the stationary element, a thread-slot formed in thehead of one of said elements and a finger carried by the head of theother of said elements, said finger being adapted to project across themouth of the slot when the elements are moved relative to each other,and operative connections between said movable element and saidlooper-bar whereby the movable element is actuated in timed relation tosaid looper.

2. In a sewing machine having a Work-arm, a looperbar slidingly andpivotally mounted intermediate its ends within the work-arm, a loopersecured to the looper-bar, and actuating mechanism adapted to impartsliding and pivoting motions to said looper-bar to impart four-motioncycles of movement to the looper-bar to produce movement of said looperabout a substantially elliptical path the major axis of which islongitudinally of the worksupport and the long sides of which constituteloop-seizing and loop-shedding movements, a stationary element carriedby the Work-support including a head located adjacent the forward edgeof the looper when at the end of its loop-seizing motion, a movableelement pivotally carried by the work-support and including a headlocated adjacent the head of the stationary element, a thread-slotformed in the head of one of said elements and a finger carried by thehead of the other of said elements, said finger being adapted to projectacross the mouth of the slot when the elements are moved relative toeach other, and operative connections between said movable element andsaid looper-bar whereby the movable element is actuated in timedrelation to said looper.

3. In a sewing machine having a needle and a looper, a needle-thread anda looper-thread carried by the needle and looper respectively, actuatingmechanisms to drive the needle and looper through two-threadchain-stitch cycles during which said needle is adapted to be projectedbetween two limbs of a triangle in the sewing threads, a loop-detainerincluding a releasable locking means for seizing and holding thelooper-thread as the looper is being moved away therefrom, said lockingmeans comprising a first element having a thread slot therein and asecond element having a finger adapted to be projected across the mouthof the thread slot for closing the same, at least one of said elementsbeing movable, and actuating means for producing relative motion betweenthe first and second elements in timed relation to the actuation of theneedle and the looper.

4. In a sewing machine having a needle and a looper, a needle-thread anda looper-thread carried by the needle and looper respectively, actuatingmechanisms to drive the needle and looper through two-threadchain-stitch cycles during which said needle is adapted to be projectedbetween two limbs of a triangle in the sewing threads, a loopdetainerincluding a releasable locking means for seizing and holding thelooper-thread as the looper is being moved away therefrom, said lockingmeans comprising a first element having a thread slot therein and asecond element having a finger adapted to be projected across the mouthof the thread slot for closing the same, at least one of said elementsbeing movable, and actuating means for producing relative motion betweenthe first and second elements in timed relation to the actuation of theneedle and the looper, said actuating means comprising operativeconnections between the movable element of said locking means and thelooper-actuating mechanism.

5. In a chain-stitch sewing machine, a threaded looper havingloop-seizing and loop-shedding movements, a threaded reciprocatoryneedle adapted to be actuated in timed and spaced relation with respectto said looper through a stitching cycle during which said needle isadapted to enter between two limbs of a triangle in the sewing threads,looper-thread detaining means comprising a releasable locking meanshaving a pair of relatively movable locking elements for seizingthe'looper-thread between the looper and the last stitch set in the workand for holding the looper-thread as the looper is moved away from thelocking means to form a thread triangle into which the needle may enter,and means for actuating said locking means in timed relation to theactuation of said looper.

wise return movement, a threaded reciprocatory needle adapted to beactuated in timed and spaced relation with respect to said looperthrough a stitching cycle during which said needle is adapted to enterbetween two limbs of the looper-thread in the formation of a two-threadchain-stitch, looper-thread detaining means comprising a locking meansconstructed and arranged to receive the limb of the looper-threadbetween the looper and the last stitch set in the work during theloop-seizing movement of said looper, and actuating means for saidlooperthread locking means to close the same and to lock thelooper-thread against withdrawal therefrom during the loop-spreadingmovements of the looper, to hold positively the looper-thread duringloop-shedding movements of the looper, and to release the looper-threadduring the sidewise return movements of the looper.

7. In a chain-stitch sewing machine, a threaded looper, actuatingmechanism for imparting a four-motion cycle of actuation about asubstantially elliptical path to said looper, said cycle of actuationincluding an endwise loopseizing movement, a sidewise loop-spreadingmovement, an endwise return loop-shedding movement and a sidewise returnmovement, a threaded reciprocatory needle adapted to be actuated intimed and spaced relation with respect to said looper through astitching cycle during which said needle is adapted to enter between twolimbs of the looper-thread in the formation of a two-threadchain-stitch, looper-thread detaining means comprising a locking meanshaving a pair of relatively movable cooperating locking elementsconstructed and arranged to receive the limb of the looper-threadbetween the looper and the last stitch set in the work during theloopseizing movement of said looper, and actuating means for saidlooper-thread detaining means to close the same and to lock thelooper-thread against withdrawal therefrom during the loop-spreadingmovements of the looper, to hold positively the looper-thread duringloop-shedding movements of the looper, and to release the looperthreadduring the return movements of the looper.

8. In a sewing machine, a threaded looper actuated through asubstantially four-motion stitching cycle including loop-seizing,loop-spreading, and loop-shedding movements, said looper being actuatedin timed relation to the actuation of a cooperating threaded needle toenchain the threads of the looper and the needle to form a twothreadchain-stitch in a stitching cycle during which said needle is adapted toenter between two limbs of the looper-thread, looper-thread-detainingmeans comprising locking means having a pair of relatively movablecooperating locking elements for receiving the limb of the looper-threadbetween the looper and the last stitch set in the work, and actuatingmeans for said locking means to close the same and to hold positivelythe looper-thread as the looper is being moved away from said lockingmeans.

9. In a sewing machine, a threaded looper actuated through ,asubstantially four-motion stitching cycle including loop-seizing,loop-spreading, and loop-shedding movements, said looper being actuatedin timed relation to the actuation of a cooperating threaded needle toenchain the threads of the looper and the needle to form a two-threadchain-stitch in a stitching cycle during which said needle is adapted toenter between two limbs of the looper-thread, andlooper-thread-detaining means comprising a locking means having a pairof cooperating locking elements consisting of a stationary element and amovable element cooperating therewith to lock a thread from being freelywithdrawn therefrom, one of said eleas the looper is being moved awayfrom said locking 5 means.

References Cited in the file of this patent UNITED STATES PATENTS ZeierMar. 6, 1934 Riviere et a1. July 7, 1936

